1. Field
The following description relates to an optical lens, and more particularly, to a varifocal fluidic lens and a method of manufacturing the same.
2. Description of the Related Art
With the development of digital technologies, digital convergence continues to increase. Digital convergence has occurred most in the fields of media and communication. An example of a digital convergence product is a mobile communication device, in which an image pickup device such as a digital camera or a digital camcorder is coupled to the mobile communication device in addition to an apparatus having functions including: games, music playback, broadcast reception, and internet browsing. In general, other similar image pickup devices may be mounted on other types of mobile electronic device such as laptop computers or personal digital assistants (PDA).
Such mobile electronic devices having an image pickup device have become increasingly compact and slim line. Moreover, other digital electronic devices, for example, MP3 players, moving picture players or digital multimedia broadcasting (DMB) televisions are commonly mounted on the mobile communication device in addition to the image pickup device. For this reason, demands for an image pickup device which are increasingly compact and slim line continually grow. A wafer-level image pickup device is a small-sized camera module newly invented to satisfy such demands for miniaturization, slimness and economic efficiency.
When image pickup apparatuses originally started to be combined with mobile electronic devices, demands for high performance image pickup devices were not high. However, in recent times, in order to satisfy growing user demands for mobile electronic devices having a high quality image pickup device, mobile electronic devices having an image pick up device have become diversified. For example, different from the early days in which the limit of a close up function was 60 cm and a focal distance was fixed, in recent times, an auto-focusing function or a zoom function, and a shooting function at a close range below 30 cm are desired by users to be provided in such an image pickup device.
In order to implement an auto-focusing function, a zoom function and a close up function, a focal length of a lens needs to be changed. As an example of methods of varying a focal length in a wafer-level image pickup device, a fluidic lens also called a liquid lens has been suggested. The fluidic lens is formed by injecting an optical fluid into a membrane. In more detail, the fluidic lens changes a thickness of a lens portion of a membrane, that is, a curvature of a lens by applying a predetermined force to optical fluid filled in a membrane. Such a liquid lens can be fabricated to have a small structure, and is suitable for use as a varifocal optic lens used in a wafer-level image pick device.